Straightening rails



til

rarest srnarenrnnnie RAILS.

seaeoi.

No Drawing.

To all whom it may concern Be it known that I, Enwann F. KENNEY, a citizen of the United States, residing in the city of Philadelphia, in the county of Philadelphia and State of Pennsylvania, (whose post-oilice address is Philadelphia, Pennsylvania,) have invented certain new and useful Improvements in Straightening Rails; and I do hereby declarethe following to be a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to the straightening of metal bars of various shapes and sizes, but with particular reference to steel rails, and in order to simplify the description, I will hereafter refer only to steel rails, but wish it understood that my invention will apply equally to other products.

After rails have been'rolled in a rolling mill, they are ordinarily placed upon cooling beds and allowed to attain the surrounding atmospheric temperature, which results in first cooling the exterior portions while the interior is hot, and after the hot interior further cools, the contraction thereof is resisted by the previously cooler exterior, with the result of setting up stresses which may afterward so add to the stresses of service as to shorten the life or usefulness of the rail.

In conducting my process I form the rails in the usual. way by rolling and finishing the same at temperatures permitting the plastic flow of the material, and generally speaking, the rails emerge from the finish ing passes of the rolling mill at a good red heat approximately 1700 to 1900 degrees Fahrenheit. Heretofore rails have been run at this red heat through a cambering machine, so that when they are cool they are approximately straight, the reason for this cambering being that the thicker hot portions cool later than the thinner portions and this camber or curvature is given so that they will draw substantially straight when cold or at atmospheric temperature.

As difierent rails when emerging from the rolling mill are apt to be at slightly different temperatures and the amount of cam ber given is necessarily substantially the same, it follows that they will not all be exactly straight when cool, so that heretofore after cooling they have been run through other straightening machines,

Specification of Letters Eatent.

Fatented Dec. as, race.

Application filed November 19, 1919. Serial No. 339,163.

either a gag press or a roller straightening machine to finally straighten them. With the heavier weight rails this straightening is done in a gag press, and with the lighter rails in some cases by a roller straightener, but this practice of cold straightening does not produce the best results.

At certain temperatures the elastic limit of steel of different qualities is very much less than when cold and at such higher temperatures rails can therefore be straightened with less pressure and at lesser stresses. The elastic limit of rail steel, particularly at ordinaryblack hot temperatures, is very much lower when at about 800 degrees Fahrenheit, or at temperatures substantially between 600 to 900 degrees Fahrenheit than at ordinary or lower temperatures.

For example, rail steels of about .71 per cent. carbon which ordinarily at the usual or atmospheric temperatures, have an elas t1c limit of 60,000 lbs. per square inch, have an elastic limit of only about 38,000 lbs-at about 800 degrees Fahrenheit.

In accordance with my invention, I roll the rails in a rolling mill in the usual way and allow themto accumulate on a cooling bed where their temperature will gradually decrease from the finishing temperature of 1700 to 1900 degrees to temperatures between 500 degrees and 1000 degrees Fahrenheit, and I then straighten or slightly camber them on a roller straightener or otherwise to such alinement or curvature as will result in a substantially straight rail when cold, thereby obviating the necessity of any further cold straightening whatsoever. By this means I work the material when its elastic limit is low as compared with what it is in a cold state, but at such temperatures that the alinement or curvature given will be maintained temporarily until the further cooling to atmospheric temperature draws the bar into such shape that it is substantially straight. If in doing this, the rails should have a ver slight curve, this would be in the form of a uniform small camber from end to end and this would be eliminated when the rails are spiked down in alinement and bedded in the track. The advantage of straightening rails between the temperatures stated is due to the fact that at such temperatures the elastic limit of the,

materalis low and the material is therefore better adapted for straightening, the temperatures selected being those known as black-heat; and straightening, curving or cambering rails at such time will produce the required alinement, as at such temperatures the rail may be straightened, curved or cambered and maintain the shape given to it thereby, but temperatures as high as or higher than 1,000 degrees Fahrenheit or thereabout would cause the rails to become so plastic that they would be distorted in handling, and they would not have or maintain the alinement desired. 7

By this means, I obviate setting up any undue initial stresses, thereby lengthening the life and service of the material.

After the rails are cooled to atmospheric temperature, they may be drilled and their ends finished as usual.

I prefer to arrange the straightening of 0 my rails or the cambering of the same between the temperatures stated in such a way that the rails when cold or at atmospheric temperature are either substantially straight or if slightly cambered or curved, this camher would be convex on the head side, so that when the rail is laid on the track in proper position with head upward the weight and the spikes will tend to draw it down straight on the ties, which of course are bedded in alinement.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. The process of treating rails which consists of rolling and finishing them at the usual customary red heat, then allowing them to cool to temperatures between 500 degrees and 1000 degrees Fahrenheit, then slightly cambering them while at such temperaturesby roller machine or otherwise, so that when cold they are substantially straight.

2. The process of treating rails which consists of straightening them at temperatures between 500 degrees and 1000 degrees Fahrenheit.

3. The process of treating rails which consists of straightening them at temperatures between 700 degrees and 900 degrees Fahrenheit.

4:. The process of treating rails which consists in straightening or slightly cambering them in a roller straightener when at temperatures between 500 degrees and 1000 degrees Fahrenheit, so that when cooled to atmospheric temperatures they are substantially straight or of slight uniform camber, preferably in an upward direction.

In witness whereof]: hereunto affix my signature.

EDWARD F. KENNEY'. 

